Traditionally, mountain, ski-touring, telemark, or other boots are strong, have high uppers, and are made of thick leather, in order to ensure good position-maintenance of the foot and ankle over all types of terrain, in particular fallen rocks and slopes, and good control of the sliding element when using ski, telemark, snowboard, and other skis.
These boots nevertheless have the disadvantage of being heavy, and fairly uncomfortable, and are difficult to lace around the foot because of the rigidity of the material used.
In addition, conventional practice, more specifically for glacier hiking, includes the use of so-called plastic shell boots, that is, boots in which the upper is made of a rigid synthetic material. These boots further comprise an inner, normally removable sock designed to ensure comfort of the foot inside the boot.
In this case, the foot is held by the sock by means of the deformation of the shell, which exerts stress on the sock.
Beside the difficulty of deforming the plastic shell in order to obtain the desired tightening effect, this type of boot also has the disadvantage that relative motion of the sock in relation to the shell can only the prevented, except by deforming the shell very forcefully on the sock and, thus generating strong pressures on the foot and causing discomfort.
Conventional practice, as revealed, for example, in Patent No. FR 2 678 487, encompasses manufacture of a walking boot comprising, inside an external upper, a foot-tightening device designed to hold the foot in place inside the boot independently of the external upper, which functions to protect against external conditions.
In this boot, the external upper is fitted on the top of the foot with a longitudinal opening extending from the ankle to the end of the foot, this opening being closed either by a zipper closure or by self-gripping means.
This boot does in fact clearly improve position-maintenance of the foot and inner comfort.
However, the longitudinal opening of the exterior upper on the top of the foot impairs the water-tightness of the boot as a whole.
These conventional boots also prove disadvantageous because they allow little proprioceptive sensation by the foot, as a result of the rigidity of the materials used for the upper.